A power-free passive stabilizing device working at an interface of different media includes a hollow chamber body, a limiting structure and a valve cover. The hollow chamber body has a first end, a second end, a first opening at the first end and a second opening at the second end. The limiting structure is connected to the first end of the hollow chamber body. The valve cover is limited by the limiting structure and movably disposed on the first end of the hollow chamber body to close and open the first opening. A passive stabilizing system using the passive stabilizing device is also disclosed. |